The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing tools are used to deposit material on a substrate and/or to etch material from the substrate. For example, the substrate may include a semiconductor wafer. Some substrate processing tools generate plasma during operation. Examples include plasma enhanced chemical vapor deposition (PECVD) systems, plasma enhanced atomic layer deposition (PEALD) systems, etc. Plasma may be generated in these systems using capacitively coupled plasma (CCP).
Most of the systems using CCP offer a very limited number of plasma diagnostic measurements (such as pressure, system voltages, currents, etc.) which can be used to adjust setpoint operating parameters as chamber pressure, gas flow and RF power. Furthermore, pressure, gas flow and RF power signals may not give complete characterization of the system. Such an incomplete characterization can lead to process drift. Additional system metrics are often needed for adequate system control.